The use of endoscopes for diagnostic and therapeutic purposes is well known in the medical arts. Various types of endoscopes are available for various particular applications. For example, upper endoscopes are utilized for the examination of the esophagus, stomach, and duodenum; colonoscopes are utilized for the examination of the colon; angioscopes are utilized for the examination of various blood vessels; brochioscopes are utilized for examination of the bronchi; laparoscopes are utilized for examination of the peritoneal cavity; and arthroscopes are utilized for the examination of various joint spaces. Examples of such endoscopes are provided in U.S. Pat. Nos. 2,922,415; 3,162,190; 4,076,018; 4,132,227; 4,201,199; 4,254,762; and 4,916,534.
Rigid endoscopes are typically used in laparoscopic procedures wherein the endoscope is inserted into a body cavity, e.g., a pneumoperitoneum, through a trocar. The use of endoscopes in such procedures minimizes trauma to the patient and also minimizes the expense associated with the procedure.
Although endoscopes provides tremendous advantages in the diagnosis and treatment therapy of many medical conditions, contemporary endoscopes are limited in their capability for repeated use. One problem commonly associated with such endoscopes is that of sterilization. Sterilization is necessary in order to facilitate reuse of the endoscope. In order to prevent the transmission of various pathogens, it is necessary to sterilize endoscopes between uses. This is of particular concern in contemporary times because of the threat of such viral infections as HIV and hepatitis A.
Although it is known to sterilize endoscopes with heat or chemical agents, the preferred method of sterilization is gas sterilization. In such gas sterilization process, the endoscope is subjected to a sterilizing gas introduced into a sterilizing chamber typically maintained at a temperature of approximately 45.degree.-55.degree. C. Contemporary endoscopes are particularly susceptible to heat damage occasioned during such gas sterilization.
In this regard, it is common for contemporary endoscopes to experience damage to the fiber optic imaging bundle disposed therein when subjected to the elevated temperatures associated with gas sterilization. Contemporary sterilization protocol requires that endoscopes be heated to approximately 45.degree.-55.degree. C. This is sufficient to cause the elongate cannula within which the fiber optic imaging bundle is disposed to thermally expand, i.e., increase in length, so as to stretch the enclosed fiber optic imaging bundle to the point where the stress within the fiber optic imaging bundle generated by such stretching causes the fiber optic imaging bundle to crack, break, or otherwise degrade.
As such, it would be beneficial to provide an endoscope which is capable of tolerating the elevated temperatures involved in gas sterilization without experiencing breakage or other degradation thereof.